Three major technologies are currently being used for concentrating solar power generation to produce useful work; the parabolic trough, the power tower, and the sterling dish. The costs of generating electricity from these power sources are high. All three require a high working temperature, which creates problems with maintenance and seal failure rates. With these technologies, the solar radiation is concentrated at the time of collection requiring a high working temperature at the point of collection. This higher temperature generally leads to higher thermal losses, which typically forces the use of more expensive and complicated collectors and thermal storage units. This constraint leads to higher costs for construction of these devices.